Circulus in Demonstrando (circular argument) and Petitio Principii (begging the question).. By: Ashley Lewis

Circular Argument This fallacy occurs if you assume the basis of the argument and the conclusion which you wish to reach. Often, the proposition is rephrased so that the fallacy appears to be a valid argument. In other words arguing in a circle is first using a premise to prove a conclusion, and then using the conclusion to prove the premise This fallacy occurs if you assume the basis of the argument and the conclusion which you wish to reach. Often, the proposition is rephrased so that the fallacy appears to be a valid argument. In other words arguing in a circle is first using a premise to prove a conclusion, and then using the conclusion to prove the premise

Begging the question This fallacy occurs when the premises are at least as questionable as the conclusion reached. Typically the premises of the argument assume the result of what is trying to be proven. This fallacy occurs when the premises are at least as questionable as the conclusion reached. Typically the premises of the argument assume the result of what is trying to be proven. The truth of A is assumed within the original premise about A. But A is not really proven by the argument. The truth of A is assumed within the original premise about A. But A is not really proven by the argument. This may occur in a simple statement or a more complex statements that go around in a circle and eventually 'prove' the original statement to be true. This may occur in a simple statement or a more complex statements that go around in a circle and eventually 'prove' the original statement to be true.

Circular argument (example) “Marijuana is illegal in every state in the nation. And we all know that you shouldn't violate the law. Since smoking pot is illegal, you shouldn't smoke pot. And since you shouldn't smoke pot, it is the duty of the government to stop people from smoking it, which is why marijuana is illegal!” “Marijuana is illegal in every state in the nation. And we all know that you shouldn't violate the law. Since smoking pot is illegal, you shouldn't smoke pot. And since you shouldn't smoke pot, it is the duty of the government to stop people from smoking it, which is why marijuana is illegal!” Circular arguments are always illegitimated.The best strategy for pointing out a circular argument is to make sure you can state clearly the proposition being proven, and then point out where the proof is in the proposition. Circular arguments are always illegitimated.The best strategy for pointing out a circular argument is to make sure you can state clearly the proposition being proven, and then point out where the proof is in the proposition. In other words, the writer is trying to tell the reader that X is true because X is true! But the writer doesn’t tell the reader why it's true. In other words, the writer is trying to tell the reader that X is true because X is true! But the writer doesn’t tell the reader why it's true.

Begging the Question (example) “ The fact that we believe pornography should be legal means that it is a valid form of free expression. And since it's free expression, it shouldn't be banned." “ The fact that we believe pornography should be legal means that it is a valid form of free expression. And since it's free expression, it shouldn't be banned." This begs the question of what free expression means. This is a misuse of terminology, and then a conclusion is reached on the matter without the question even being answered. This begs the question of what free expression means. This is a misuse of terminology, and then a conclusion is reached on the matter without the question even being answered.

How to avoid the fallacies There are three parts to good argumentative writing: There are three parts to good argumentative writing: 1.Premises : assumptions the argument is built on; or to look at it another way, the reasons for accepting the argument. 2.Inference : you start with one or more suggestions which have been accepted and explained in great detail; you then use those proposals to arrive at a new proposition. 3.Conclusion :The conclusion is to be confirmed on the basis of the premises, and the inference from them. In every piece of argumentative writing these three components will ensure a fallacy free paper.

Citation Cline, Austin. "Fallacies of Presumption." Agnosticism / Atheism. ©2009 About.com. 6 Apr 2009 Cline, Austin. "Fallacies of Presumption." Agnosticism / Atheism. ©2009 About.com. 6 Apr 2009 Mathew. "Logic & Fallacies: Constructing a Logical Argument." secular web library. infidels. 6 Apr 2009 Mathew. "Logic & Fallacies: Constructing a Logical Argument." secular web library. infidels. 6 Apr 2009 Mesher, David. "Introduction to Fallacious Appeals." MISSION CRITICAL. san jose state university. 6 Apr 2009 Mesher, David. "Introduction to Fallacious Appeals." MISSION CRITICAL. san jose state university. 6 Apr 2009 Whitman, Glen. "Logical Fallacies and the Art of Debate." DEBATE. 29 January Economics California State University, Northridge. 6 Apr 2009 Whitman, Glen. "Logical Fallacies and the Art of Debate." DEBATE. 29 January Economics California State University, Northridge. 6 Apr 2009